John MacDonald hurled a bottle containing petrol or other flammable liquid through the window of a house in Elgin, Moray, injuring all of those inside.
A judge told shaven-headed MacDonald: "You continue to deny responsibility and in keeping with that position you have exhibited no remorse."
Lord Angus Stewart added at the High Court in Edinburgh: "The only proper sentence is a long period of imprisonment."
The judge said he noted that 43-year-old MacDonald had a criminal record but added there "nothing approaching the seriousness" of the latest offence.
MacDonald, from Elgin, but currently in prison, had earlier denied attempting to murder Alistair Brooks, Anne Roate, Daniel Doherty, Lisa Sharp and George Lindsay by wilfully setting fire to a flat in Kingsmills, Elgin, on December 12 last year, but was found guilty by a jury.
The judge noted that four of the victims escaped with relatively minor injuries but that Mr Brooks suffered burns over a quarter of his body and continues to receive treatment. He said the jury had accepted the lives of all those in the flat at the time of the bombing were endangered.
The fire brigade was at the scene quickly and a firefighter rescued Mr Brooks from the blaze which also damaged an upstairs property.
The court heard MacDonald had previously been dating Ms Sharp but she had started a relationship with Mr Lindsay before the murder bid.
The judge said the motivation appeared to be a grudge MacDonald bore against Mr Lindsay.
He said there was no evidence of animosity between him and the others but the attack involved risk to all in the house.
Lord Stewart said there must have been a degree of planning involved in the offence, with the inference being that MacDonald tracked down Mr Lindsay and armed himself with the fire bomb.
Sentence had been deferred on MacDonald until yesterday following his earlier trial for the preparation of a background report on him.
Defence counsel Tony Graham said although MacDonald had previous convictions there was "nothing indicative of a pattern of public harm".
He added: "What we have is a one-off incident, albeit one that is serious."
He claimed MacDonald had led a fairly uneventful life and had a reasonable work record.
Mr Graham said: "We heard in evidence there were issues over a young lady. When he is released he will be a wiser and older man."
Detective Inspector Stewart Mackie, of Grampian Police, said: "Mr Macdonald has shown no remorse for his actions, the consequences of which were potentially fatal."
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